While learning OpenSCAD, I realized that there was no convenient way to remember which axis traveled horizontally through each view (Top, Bottom, Left, Right, Front, Back), so I made a simple 5cm cube that can sit on my desk and remind me. It is more for when I am importing/exporting to/from other programs, so I can wrap my object in the proper 'rotate([]) {}' to make sure that it is properly orientated for whatever end program I am using (Unity3D/UE4/etc.)